Image forming devices often have door panels disposed about the exterior housing of the device. These door panels may be opened and closed as needed to access the interior of the device. For example, door panels may be provided to feed specialty media sheets, clear paper jams, and replace consumable items. In the latter two examples, the door panels may be opened just long enough to perform the necessary task. That is, a user may open the door panel, clear a paper jam or replace a component such as a toner cartridge, and then close the door to resume operation.
In other instances, the door panel may remain open for extended periods. One example is a multipurpose door that may be used periodically to feed specialty media such as forms, envelopes, or transparencies into the image forming device. Certain multipurpose media door panels are designed so they do not interfere with normal operation of the image forming device and may remain open indefinitely. Thus, for users who regularly feed specialty media into the multipurpose feeder, there is no absolute need to open and close the multipurpose door panel each time the multipurpose feeder is used.
Door panels in image forming devices may be designed to open a limited amount to prevent damage to door hinges. Often, a mechanical interference such as a detent or a hard stop is used to limit door travel. Unfortunately, door panels are sometimes opened beyond their intended range of travel. Items may be dropped on an open door panel or persons may lean or bump into the open door panel. In a worst case, the door hinges are destroyed and the damaged parts must be serviced and replaced. This scenario results in unwanted downtime. Some designs use a breakaway feature that permits travel beyond the intended range. For example, plastic snaps or other integrated latches may release their hold if a sufficient force is applied to the door panel. Afterwards, the door panel may be returned to its initial state. Unfortunately, snaps, latches, and other release mechanisms are subject to cyclic fatigue and may ultimately break after a certain number of cycles.
Furthermore, certain types of breakaway mechanisms rely on a tightly controlled fit between two or more parts. Thus, the parts must be manufactured to exacting processes and material standards. Problems such as material defects, tooling errors, and poor process control may lead to high failure rates. At one extreme, the breakaway mechanism may not release as intended, resulting in damage that the mechanism was intended to prevent. At another extreme, the breakaway mechanism may release too easily and door panels may not stop at the intended limit. This latter example may be particularly problematic for multipurpose door panels as they may not be able to support the weight of specialty media.
An added problem arises as image forming devices are incorporated in smaller packages. Rigid space constraints tend to limit size and placement of door panels. In certain instances, there may be some amount of overlap between one or more door panels. In other instances, there may be door panels disposed within door panels. In these cases, one door panel may need to be closed before opening another. If these door panels are not opened or closed in the proper order, a resulting interference between the door panels may force one or more panels to open past their intended range of travel. As these types of compound door designs become more common, the importance of a robust breakaway design increases. Existing breakaway mechanisms may not provide an optimal solution for these problems.